The invention is in the field of machines for processing recyclable material, and particularly concerns machines that separate paper, bulk containers, broken glass and other materials.
More specifically, the invention relates to a disc screen apparatus for classifying material in a stream of heterogeneous materials. More specifically still, the invention concerns a disc screen apparatus with discs that may be mounted to and removed from the apparatus without disassembly of the apparatus.
Material recycling has become an important industry in recent years due to decreasing landfill capacity, environmental concerns and the dwindling of natural resources. Many industries and communities have adopted voluntary and mandatory recycling programs for reusable materials. Solid waste and trash that is collected from homes, apartments or companies often combine the recyclable materials into one container, usually labeled "RECYCLABLE MATERIAL". Recyclable materials include newspaper, magazines, aluminum cans, glass bottles and other materials that may be recycled. When brought to a processing center, the recyclable materials are frequently mixed together in a heterogenous mass of material. Ideally, the mixed materials should be separated into common recyclable materials (i.e., papers, cans, etc.).
Disc screens are increasingly used to separate heterogeneous streams of recyclable material into respective streams or collections of similar materials. This process is referred to as "classifying", and the results are called "classification".
A disc screen apparatus typically includes a frame in which a plurality of rotatable shafts are mounted in parallel. A plurality of discs are mounted on each shaft and means are provided to rotate the shafts commonly in the same direction. The discs on one shaft interleave with the discs on an adjacent shaft to form screen openings between the peripheral edges of the discs and structures on the adjacent shaft. The sizes of the openings determine the size (and thus the type) of material that will fall through the screen. Rotation of the discs carries the larger articles along or across the screen in a general flow direction from an input where a stream of material pours onto the disc screen to an output where those articles pour off of the disc screen.
In disc screen apparatuses that are used for classification of recyclable materials I have found that the heavy continuous flow of recyclable material tends to result in quick wear and a significant degree of damage to the discs, requiring a high level of maintenance and repair. My observation is that the discs are typically slidably engaged to their shafts, fixed in their positions by spacers, and retained in the shafts by clamping applied to the ends of the shafts. Therefore, to replace a damaged disc, the shaft on which the disc is mounted must be disassembled from the screen, the disc slid off the shaft and replaced, and the shaft reassembled to the screen. Much time is consumed in this process.